[15] In fairness to retailers I should state that the price of arrowroot just now is unusually low; the ordinary range is from twopence to two shillings. People who are afraid of having their arrowroot adulterated should ask themselves what can be used to cheapen the St. Vincent at the above-quoted prices, which are those of the unquestionably genuine article. CHAPTER XII. GLUTEN—BREAD. HAVING treated the cookery of the chief constituents of the roots and stems of the plant, the fibre and the starch, I now come to food obtained from the seeds and the leaves. Taking the seeds first, as the more important, it becomes necessary to describe the nitrogenous constituents which are more abundant in them than in any other part of the plant, though they also contain starch and cell material, or woody fibre, as already stated. In the preceding chapter I described a method of separating starch from flour by washing a piece of dough in water, and thereby removing the starch granules, which fall to the bottom of the water. If this washing is continued until no further milkiness of the water is produced, the piece of dough will be much reduced in dimensions, and changed into a grey, tough, elastic, and viscous or glutinous substance, which has been compared to bird-lime, and has received the appropriate name of _gluten_. When dried, it becomes a hard, horny, transparent mass. It is insoluble in cold water, and partly soluble in hot water. It is soluble in strong vinegar, and in weak solutions of potash or soda. If the alkaline solution is neutralised by an acid, the gluten is precipitated. If crude gluten, obtained as above, is subjected to the action of hot alcohol, it is separated into two distinct substances, one soluble and the other insoluble. As the solution cools, a further separation takes place of a substance soluble in hot alcohol but not in cold, and another soluble in either hot or cold alcohol. The first, viz. that insoluble in either hot or cold alcohol, has been named _gluten-fibrin_; that soluble in hot alcohol, but not in cold, _gluten-casein_; and that soluble in either hot or cold alcohol, _glutin_. I give these names and explain them, as my readers may be otherwise puzzled by meeting them in books where they are used without explanation, especially as there is another substance presently to be described, to which the name of ‘vegetable casein’ has also been applied. The gluten-fibrin is supposed to correspond with blood-fibrin, gluten-casein with animal-casein, and glutin with albumen. Their composition is as follows, which I append for what it is worth in connection with this theory, but mainly to show how small is the difference between the chemical composition of the nitrogenous constituents of animals and those of plants. I shall come to this subject again: